Has Anyone had a Problem with the QB Fuselage and attaching Horizontal Stab?

The following is a copy of my email to Van's Support. I am posting this to see if anyone else has had this problem with their RV-6QB fuselage. Any suggestions? Thanks for any suggestions!

Van's responded and their answer is at the bottom, #7.





"I am attempting to finish my RV-6 and hope to not be the last one completed! I started in ’96 and am working on the fuselage QB right now. I am attempting to attach the horizontal stab to the fuselage and have run into a snag. Per Drawing 34, I drilled a pilot hole, #40, thru the HS-610, 1/8” spacer, F-614 aft top deck, longeron and, I thought, thru the 1x1x1/8” 6061-T6 bracket which lies underneath the aft top deck.

"I checked my pilot hole and found that the 6061-T6 bracket was trimmed improperly and does not nest against the longeron. There is a gap of at least 5/32” between the longeron and the edge of the bracket. This gap, if left untouched, will result in the outboard bolt on each side not going through the 6061-T6 bracket underneath the top deck. I believe that this is unacceptable, based upon the forces applied to the horizontal stab in flight.

"I received my QB fuselage in November, 2003, so I know that the -6 fuselage option is probably no longer in production. If any are still being produced, however, I would like someone to check this area so that there is not a repeat of my problem.



"I have taken photos of this area and attached a few. More photos are available on my photo web site at: http://picasaweb.google.com/bakerfamilyenator/EmpennageAttachedToFuselage#

"As of right now, I believe that the correct fix is to remove the aft top deck and replace the 6061-T6 bracket with a properly trimmed bracket."

Replacing bracket

Gary

I didn't have a quick build but I did replace this bracket after I had completed the fuse. ( I realised I had made an error when making the bracket).
To be honest it was no big deal, About 2 hours work at the most.
I simply drilled out enough rivets to remove the top deck and bracket then riveted the new one on and replaced the deck.
Most rivets could be squeezed and I think from memory I used two pop rivets on the bracket where it was just a little to tight to rivet.

I know myself I'd replace it and have it right for peace of mind. I spent more time thinking about it than actually fixing the problem.

Cheers

Peter

Gary, while fitting the new angle bracket, either cleco the top deck back in place, or use the top deck as a template to make a strap brace across the work area so the longerons don't get slightly bowed out while you're trying to get a good snug fit in this area. At least when you're done making the new angle and have it clecoed in place, check the fit of the top deck to make sure you haven't widened this area and everything still lines up OK. Don't ask me how I know this.

Same on the 8QB

I had this issue on my -8QB. I had read other builder sites and new this angle had to be made properly to prevent any ED issues. When I looked at mine it was well short. I took the old one out by drilling the rivets from the shop head side. It was the only way to get the angle out without taking off the entire aft deck. Luckily Van's included an angle with for several PP parts and this angle was in there. I did note that if you trim the angle with the PP guide holes the angle will come out shorter than it should, I ignored the holes.

I was also surprised to see that the angle that I took out was not deburred very well, there were deep file marks on the hidden part of the angle. I plan to take this to Van's when I pick up my finish kit and talk with them about the QC at the QB shop.

You can read about my issue on my 9/22-23/08 entries.

Cheers

Thanks ...

for the suggestions and help!

Another solution...

...that is apparently approved by Vans. The "inside doubler fix"...

I remembered this cropping up before, and a Matronics search came up with this from 2004....

Mickey:
The same thing happened to me. Mine is QB and when they built that
section they just didn't overlap the angle enough with the longeron. So,
I drilled the hole properly centered in the longeron and it came out
looking exactly like your picture on the inside. Given the dimensions
of that angle that's rivetted in there, you don't have much choice.

On the advice of Vans I cut a strip of 1/8" 6061 Aluminum (I cut it out
of a piece of angle I had laying around) and made it long enough so that
it fit over those last 2 bolt holes. I was careful to make it extend as
far outboard as it could and then drilled it to the 2 existing holes.
I had to do that on each side. So, I have these 2 extra piece of 1/8"
AL in there forevermore. It serves as a sort of doubler and gives
adequate edge distance (well, much better edge distance, anyway) and a
sound place to tighten the bolt against.
--
Tom Sargent, RV-6A canopy.

Van's Response

FWIW to anyone in the future: I received the following response from Joe Blank @ Van's with two alternatives:

"I wanted to get engineering's input. As I suspected the issue is not too serious...

"There are essentially 2 different fixes that we could apply here. We have seen this before in both QB and Standard Build fuselages, in both cases the 1x1x1/8" angle was made too short to provide little if any edge distance for the AN3 bolts that co-join the longerons and the H/S attach angle.

"Fix 1 is to do essential what you have suggested. Drill out the old angle and fabricate and install a new longer angle. We can provide and ship you the raw angle at no charge.

"Fix 2 is to fabricate a AS3-125x3/4x11 that will laminate under the AA6x1x1 angle that is too short, but that runs entire length from longeron to longeron. Then just use longer bolts to attach the H/S as well as 2 additional bolts through the Aft Deck, 1x1 angle, and the new .125 sheet. This will provide an adequate load path for the assembly."

I personally am going with Fix 1. I would suggest to builders of QB's to double-check these brackets to ensure that the HS bolts are going thru all the material they are supposed to.

Thanks for everyone's suggestions with this!